The holiday season is a special time filled with fun, family, friends and festivity. From office parties to family gatherings, there are plenty of times and places to celebrate and, for those who choose to use alcohol as part of their celebrations, plenty of opportunities to overindulge.

But though drinking might seem fun at the time, the next morning hangover is nothing to laugh about. Common symptoms of a hangover include headache, nausea, vomiting, diarrhea, thirst, sensitivity to light and noise, sweating, anxiety, irritability, trouble sleeping, difficulty concentrating and erratic motor functions, including tremors.

Some hangover symptoms are due to the direct effects of alcohol on the body, while others result from the body’s efforts to cope with the removal of alcohol and counteract its depressant effects on the central nervous system.

There are a number of factors that can affect how severe a hangover might be, such as the amount of alcohol consumed, at what rate, and how much food and water is consumed while drinking. And, according to a new study, a person’s liquor choice might also help determine the intensity of a hangover.

Although quite prevalent, hangovers have not been extensively studied. So to better understand the effects of alcohol, specifically the levels of toxic substances called congeners in the alcohol, researchers at the Brown University Center for Alcohol and Addiction Studies in Providence, Rhode Island, and the University of Michigan Medical School recruited 95 healthy heavy drinkers, 58 men and 37 women, between the ages of 21 and 33 residing in the greater Boston area. Prior to the study, none of the participants had ever been treated for alcohol-related problems, and none had experienced any form of sleep disorders.

The study was carried out over two evenings, a week apart. In the 24-hour period before each of these evenings, the participants were required to abstain from alcohol, illicit drugs, sleep aids and caffeine.

On one night, the participants consumed either 100 proof Absolut vodka, which contains relatively few congeners, or 101 proof Wild Turkey bourbon, which has about 37 times more congeners than vodka, until their breath alcohol concentrations (BrAC) levels reflected inebriation. Another night they drank an alcohol-free placebo beverage.

Overnight their sleep was monitored and the following morning they were asked to rate their hangover in terms of severity, ranging from little or no impact to incapacitating. They were also asked to perform tasks to access speed, vigilance and concentration skills and their polysomnography recordings were assessed.

Bourbon drinkers reported a worse hangover than those who drank vodka, suggesting that higher congener levels increase the intensity of the hangover. Alcohol also impaired the participants’ performance on the cognitive tasks and disrupted sleep, but there was no difference between the two alcoholic drinks.

Most participants did not think that their driving ability was impaired in the morning. However, they said they would be less willing to drive the morning after alcohol than after placebo.

“The most important thing for people to realize is that if you’re feeling hung-over, you’re probably impaired in terms of performing tasks that require vigilance and making quick decisions,” said study author Dr. Damaris J. Rohsenow, associate director of the Center for Alcohol and Addiction Studies at Brown University. Rohsenow added that while people who drink to inebriation will still get hung-over from vodka or white wine, they “are going to feel sicker after drinking an alcohol—such as bourbon—which is among the darker liquors, and therefore has a lot more naturally toxic poisons in it.”

Dr. Marc Galanter, a professor of psychiatry at New York University School of Medicine in New York City, agrees that overindulgence is the root cause of a hangover, regardless of alcohol choice.

“What’s clearly emerged is that it’s the alcohol content that is the most salient factor in terms of damage and long-term damage and addiction,” he said. “It’s the actual amount of alcohol that counts. Nonetheless, we see emerging some interesting issues in terms of which congeners go along with which alcohol. For example, in terms of what produces more hangover.”

The study will be published in the March issue of Alcoholism: Clinical and Experimental Research.